Page 12 - CH6 (1)

and processed mRNA
● Regulatory genes − Sequences that do not code for anything, but have

regulatory functions

​ypes of RNA & Transcription Process
T

Types of RNA

● mRNA (messenger RNA) − It serves as a template for protein

synthesis. DNA is transcribed to form an mRNA, which in turn is
translated to form protein. [Central dogma of molecular biology]

● tRNA (transfer RNA) − It brings amino acids during translation and
reads the genetic code.

● rRNA (ribosomal RNA) − These are the work benches of translation.
They play a structural and catalytic role during translation.

Transcription Process

● Transcription has three steps − initiation, elongation, and termination.

● Initiation:
○ RNA polymerase binds with the promoter to initiate the process
of transcription.

○ Association with initiation factor (σ) alters the specificity of RNA
polymerase to initiate the transcription.

:
● Elongation​
○ RNA polymerase uses nucleotide triphosphate as substrate, and
polymerisation occurs according to complementarity.
● Termination:

○ Termination occurs when termination factor (P) alters the
specificity of RNA polymerase to terminate the transcription.
● As the RNA polymerase proceeds to perform elongation, a short
stretch of RNA remains bound to the enzyme. As the enzyme
reaches the termination region, this nascent RNA falls off and
transcription is
○ terminated.